1. Field of the Invention
The present invention relates to a method and an apparatus of manufacturing a one-way clutch which has sprags, a ribbon spring, an inner retainer, and an outer retainer and for which an idling state and a torque transmitting state can be set in accordance with the rotational directions of an outer ring and an inner ring, and more particularly to a technique of automating the manufacture of one-way clutches.
2. Description of the Related Art
Conventionally, in the operation of assembling a one-way clutch 20 as shown in FIG. 19A and 19B and having sprags 21, a ribbon spring 22, an outer retainer 23, and an inner retainer 24, most of the operation depends on the manual operation.
Namely, to assemble the one-way clutch 20, a predetermined number of sprags 21 are consecutively inserted and fitted into sprag inserting windows 28 provided in the ribbon spring 22 at predetermined intervals in the longitudinal direction, as shown in FIG. 20.
Next, as shown in FIG. 21, the sprags 21 are adjusted from the inner side of the outer retainer 23 to sprag inserting windows 30 provided in the outer retainer 23 at predetermined intervals along the circumferential direction of the outer retainer 23. Then, outer ring-side end portions 25 of the sprags 21 are consecutively inserted and fitted into the sprag inserting windows 30 of the outer retainer 23 in such a manner as to twist the ribbon spring 22 into which the sprags 21 have been inserted and fitted.
Further, the sprags 21 are adjusted from the outer side of the inner retainer 24 shown in FIGS. 19A and 19B to sprag inserting windows 31 provided in the inner retainer 24 at predetermined intervals along the circumferential direction of the inner retainer 24. Then, inner ring-side end portions 26 of the sprags 21 are consecutively inserted and fitted into the sprag inserting windows 31 of the inner retainer 24. These inserting operations are manually performed.
In the above-described related method, there has been a problem in that expert skill is particularly required in the operation shown in FIG. 21 in which the outer ring-side end portions 25 of the sprags 21 are inserted and fitted into the sprag inserting windows 30 of the outer retainer 23.
Namely, when the outer ring-side end portions 25 of the sprags 21 are inserted and fitted into the sprag inserting windows 30 of the outer retainer 23, it has been necessary to perform the operation by adjusting the sprags 21 from the inner side of the outer retainer 23 to the sprag inserting windows 30 of the outer retainer 23 and in such a manner as to twist the ribbon spring 22 by using of the flexibility of the ribbon spring 22. At this time, if an undue force is inadvertently applied to the ribbon spring 22, it leads to the breakage of the ribbon spring 22. Accordingly, it has been difficult to automate the operation of assembling the one-way clutches 20 through mechanization.
The present invention has been devised in view of the above-described related problem, and its object is to provide a method of manufacturing a one-way clutch which is capable of automating the operation of assembling the one-way clutch and which makes it possible to improve the productivity and stability in the quality of one-way clutches and attain labor saving.
To attain the above object, in accordance with the present invention, there is provided a method of manufacturing a one-way clutch including a plurality of sprags, a flexible ribbon spring in which sprag inserting windows for insertion of the sprags therein are formed in its longitudinal direction, an outer retainer on an inner periphery of which the ribbon spring is wound and which has sprag inserting windows into which outer peripheral-side end portions of the sprags inserted in the ribbon spring can be inserted, and an inner retainer disposed on an inner peripheral side of the ribbon spring and having sprag inserting windows into which inner peripheral-side end portions of the sprags inserted in the ribbon spring can be inserted, comprising the steps of: using a boss which is formed in a substantially hollow cylindrical shape and in which sprag pockets which are open toward a radially outward side in such a manner as to be capable of accommodating the sprags and V-shaped grooves for respectively engaging V-shaped bent portions of the ribbon spring are disposed alternately in an outer peripheral portion thereof; consecutively inserting the sprags into the sprag pockets of the boss; winding the ribbon spring around an outer periphery of the boss while the V-shaped bent portions of the ribbon spring are being respectively engaged in the V-shaped grooves of the boss; continuously rotating the boss at a predetermined number of revolutions after the outer retainer, for which a phase of the sprag inserting windows of the outer retainer is adjusted to a phase of the sprag pockets of the boss, is fitted to an outer peripheral side of the ribbon spring on the boss, thereby allowing the sprags to move from inside the sprag pockets toward the radially outward side of the boss and to be inserted and fitted into the sprag inserting windows of the ribbon spring and the outer retainer, respectively, by a centrifugal force; and fitting the inner retainer, for which a phase of the sprag inserting windows of the inner retainer is adjusted to the phase of the sprag pockets of the boss, to an inner side of the ribbon on the boss while relatively rotating the inner retainer with respect to the ribbon spring, so as to insert the sprags into the sprag inserting windows of the inner retainer.
As a result, by virtue of the centrifugal force due to the continuous operation of the boss, the sprags inserted in the sprag pockets of the boss bring about by themselves the operation of insertion and are inserted into the sprag windows of the ribbon spring and the outer retainer arranged on the outer side of the sprags with the circumferential positions of these sprag windows brought into phase relative to each other. Accordingly, by controlling the continuous operation of the boss, the insertion of the sprags is effected smoothly without applying an undue force to them.
In addition, to attain the above object, a one-way clutch manufacturing apparatus may be configured as an apparatus for manufacturing a one-way clutch including a plurality of sprags, a flexible ribbon spring in which sprag inserting windows for insertion of the sprags therein are formed in its longitudinal direction, an outer retainer on an inner periphery of which the ribbon spring is wound and which has sprag inserting windows into which outer peripheral-side end portions of the sprags inserted in the ribbon spring can be inserted, and an inner retainer disposed on an inner peripheral side of the ribbon spring and having sprag inserting windows into which inner peripheral-side end portions of the sprags inserted in the ribbon spring can be inserted, the apparatus comprising:. a plurality of bosses which are each formed in a substantially hollow cylindrical shape and in which sprag pockets which are open toward a radially outward side in such a manner as to be capable of accommodating the sprags and V-shaped grooves for respectively engaging V-shaped bent portions of the ribbon spring are disposed alternately in an outer peripheral portion thereof; consecutively inserting the sprags into the sprag pockets of the boss; an index table on which the plurality of bosses are respectively placed in an outer peripheral portion of an upper portion of a table at predetermined rotational angles; sprag inserting means provided at a first position on the index table so as to consecutively insert the sprags into the sprag pockets of the boss; ribbon-spring fitting means provided at a second position adjacent to the first position on the index table so as to wind the ribbon spring around an outer periphery of the boss while the V-shaped bent portions of the ribbon spring are being respectively engaged in the V-shaped grooves of the boss; outer-retainer fitting means disposed at a third position adjacent to the second position on the index table so as to continuously rotate the boss at a predetermined number of revolutions after the outer retainer, for which a phase of the sprag inserting windows of the outer retainer is adjusted to a phase of the sprag pockets of the boss, is fitted to an outer peripheral side of the ribbon spring on the boss, thereby allowing the sprags to move from inside the sprag pockets toward the radially outward side of the boss and to be inserted and fitted into the sprag inserting windows of the ribbon spring and the outer retainer, respectively, by a centrifugal force; and inner-retainer fitting means disposed at a fourth position adjacent to the third position on the index table so as to fit the inner retainer, for which a phase of the sprag inserting windows of the inner retainer is adjusted to the phase of the sprag pockets of the boss, to an inner side of the ribbon on the boss while relatively rotating the inner retainer with respect to the ribbon spring, so as to insert the sprags into the sprag inserting windows of the inner retainer.